Abstract

Tests for young sport horses were recently introduced in Great Britain. This study characterises the young horse data, examines their suitability for genetic analysis and estimates the genetic parameters needed for breeding value prediction.

Evaluation data from 2006-2009 were used. This included 1 887 evaluations of 1 323 horses, which were evaluated for competing in dressage, show jumping, eventing, endurance or as sport ponies. Traits assessed were conformation, correctness of paces, type and temperament, athleticism and veterinary. The distributions of traits were examined and correlations of traits between disciplines, for the effect of the horse, were estimated. These indicated that traits could be assumed to be genetically identical across disciplines. Variance components were estimated for each of the 5 traits, using an animal model, where random effects were the genetic effect of the horse and the permanent environment of the horse. Bivariate analyses were performed between pairs of traits.

Mean scores for each trait in each discipline were between 8.02 and 8.24, and standard deviations were between 0.54 and 0.83. Heritabilities ranged between 20.3% for athleticism and 42.2% for type and temperament. The variance due to the horse's permanent environment ranged from approximately 25% for correctness of paces and athleticism to 51.6% for veterinary. The genetic correlations between traits were generally high.

The young horse tests (>> Futurity <<) recently introduced in the UK are a valuable data source for genetic evaluations. The most appropriate measure will be to combine young horse data with adult competition data to routinely estimate breeding values.